The filling of portable pressure vessels with pressurized fluids, particularly gases, is a time-consuming and frequently labor intensive operation. In the case of gases, the pressure vessel is frequently first evacuated prior to filling for various reasons. Therefore, the pressure vessel must first be connected to a source of vacuum. Usually, the pressure vessel is equipped with its own inlet and outlet valve. The vacuum line is connected to the outlet of the vessel valve for the purpose of drawing down the pressure therein to the desired extent. The vessel valve is then closed and the source of vacuum disconnected from the outlet of that valve.
The vessel is then connected through its own valve to a source of pressurized gas as for instance freon. After the vessel has been filled to the desired degree, the vessel valve is closed and the source of high pressure gas disconnected.
Usually, evacuation and filling are done sequentially. If a system were to provide the capability of evacuating one tank while simultaneously filling another tank, the time required could be drastically reduced. Nevertheless, such a system, which if kept to a minimum expense would involve manually operated valves is likely to involve a substantial length of conduit between the valve system and the vessel being filled. In many instances the gas is sufficiently costly and sufficiently voluminous to warrant means for recovery.
It is among the objects and advantages of the present invention to provide both a system and method with scavenging capabilities for simultaneously filling and evacuating at least two separate pressure vessels simultaneously.
Another object of the present invention is to provide means for scavenging residual gas left in a portion of the system after filling.
Yet another object of the present invention is to employ the vacuum in the evacuated tank to scavenge residual gas in other portions of the system before initiating the filling of the evacuated tank.